Question

write in summation notation
125/9+625/16+3125/25+15,625/36+...

Answer 1

"Summary Notation"

Answer 2

Divorce the numerators from the denominators, you'll find that the numerators increase by multiplying 5 over and over again, starting at 125, or 5 cubed :D

The denominators are just the squares of all the numbers starting at 3.

:)

Answer 3

This would seem about right...
\[\huge \sum_{n=3}^{\infty}\frac{5^n}{n^2}\]

Answer 4

what if n = 1 ? cause the question says n should equal 1

Answer 5

You want it to start at n=1? :D
That can be arranged...
\[\huge \sum_{n=1}^{\infty}\frac{5^{n+2}}{(n+2)^2}\]

Answer 6

Thank you very much